Leo book



(No Model.)

L. BOOK, Jr. REUORDING AND REPR-ODUOING SQUND WAVES.

Patented June 7, 1887..

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I UNITED STATES PATENT OFFICE.

LEO BOOK, Ja, on NEW YORK, N. Y,

RECORDING AND REPRODUCING SOUND-WAVES.

SPECIFICATION forming part of Letters Patent No. 364,472, dated June 7, 1887.

Application filed Dccemler 4, 1886. Serial No. 220,692. (No model.)

To aZZ whom it may concern.-

Be it known that I, LEO BOOK, J11, a citizen of the United States, residing at New York, county and State of New York, have invented certain new anduseful Improvements in Recording and Reproducing Sound WVaves, of which the following is a specification.

In my applicationfor Letters Patent, filed December 11, 1885, under Serial No. 185,364, is described a method of producing and retransmitting records of electrical and mechanical impulses or vibrations, consisting in causing a beam of light controlled by the i1npulses or vibrations to fall upon an actinicallysensitized transparent film or plate, thereby producing the desired record, then preparing from this negative record a circuitcontroller in the form of a non-condncting perforated plate or film, and then retransmitting the original impulses or vibrations by placing the perforated non-conducting plate between a metal bed and stylus and moving it relatively to the stylus, thus allowing the stylus to make contact with the metallic bed through the perforations or openings in the non-conducting film or plate and cause to flow over the line electrical impulses or vibrations corresponding to those by which the record was originally produced.

Now, this invention, which is allied to the invention embraced in my before-mentioned application, insomuch as it embodies analogous processes and apparatus, has for its special object to record and retransmit articulate speech; and it consists, mainly, in the production of a transmitting medium composed of a conducting material provided with variable-resistance paths corresponding to the amplitude and rate of the vibrations to be retransmitted.

The best means of accomplishing the object of this invention at present known to me consists, first, in causing a beam of light, which is actuated or controlled by the diaphragm of a telephonic instrument, to vibrate on a moving film, plate, or sheet transversely to the direction of motion thereof, said plate or sheet being originally transparent, or subsequently made transparent; secondly, in producing in or on an actinically-sensitizcd con-- ducting medium variable-resistancefpaths corresponding to the rec rd produced on the film, plate, or sheet, by exposing to the action of light a suitably-prepared sensitized conducting medium under the transparent record,

and by subsequent treatment and fixing process varying its conductivity in proportion to the amount of light which passed through the record on the transparent film, plate, or sheet; and, thirdly, in retransniitting the recorded vibrations over a line by passing the variablercsistauce paths of the conducting medium between a brush or roller and a metallic bed in cluded in circuit with an electric battery and the receivirig-instrument, or preferably in circuit with a battery and the primary coil of an inductorium, the secondary coil of which is included in the linecircuit with the receivinginstrument.

For the variablercsistance circuit controller I have devised a sensitized electric conductin g film, plate,o r sheet specially adapted to the purpose, consisting of a mixture of gelatine, glue, isinglass, or other organic matter, a dichromate salt-,an electric conducting material in a finely-pulverized condition, as carbon, graphite, metals, or their electric conducting compounds, and water or other suitable solvent.

In the accompanying drawings, to which I will now refer, I show so much of apparatus adapted to the carrying out of my invention as is necessary for a full understanding of the same to be had.

Figure 1 represents in section the receiving and recording apparatus. Fig. 2 represents part of a negative record produced in the receiving and recording apparatus. Fi 3 represents part of a variableresistance circuitcontroller prepared from and being the counter or positive of Fig. 2; and Fig. 4 is a dia gram View of the essential parts of the transmitting apparatus.

The transparent material upon which the record is made is represented as a strip, a, made sensitive to the action of light by any of the wellknown photographic processes. It passes around and is moved by the drum or cylinder 1), which is rotated at a uniform speed by the clock-work or other motor, 0. The

dark box (I protects the strip a from extrane ous light and has fitted in its'side the diaphragm e, adapted to be actuated by sound waves through the mouth f. This diaphragm 6 may also be considered as the vibrating part of a telephonic receiver if the soundwaves to be recorded originate at a distance from the apparatus. This diaphragm e is caused to actuate thelightcontrolling device, which consists of a shield, 9, provided with a fine hole, h, and carried on the end of the lever z',which is pivoted at its lower end, i, to the bottom of the dark box d, so as to be capable of oscillation at right angles to the direction. of vibration ofthe diaphragm c. This lever t is connected to the center of the diaphragm e by the fine adj Listing-screw j. The shield 9 covers an opening, (2, in the end of the box cl, and oppo site this opening is located the source of light,

It, the rays of which are preferably concentrated in the opening (2 onto the shield g, which permits only such rays as can pass through the hole It to enter the dark box. A suitable arrangement of mirrors and lenses f/c 70 maybe used to direct the rays of light from, the source 70 to the opening d.

The rays of light which enter the dark box (2 through the hole h of the shield g are, when the shield g is at rest, directed upon the center of the sensitized strip a. N ow, as this strip a v is moved at a uniform rate of speed and the shield g is rocked by the action of the diaphragm e thereon at right angles to the direction of motion of the strip, the hole h, during each complete vibration of the diaphragm, allows the lateral rays of light to impinge upon the strip a on both sides of the normal central line, thus acting on the sensitive material of the strip in such a manner that when the same is developed by the ordinary photographic process a sinuous negative marking is produced thereon, as shown at Fig. 2, the altitude of the sinuositiesbeing in accordance with the amplitudes of the vibrations of the diaphragm, and their number or recurrence in accordance with the rates of the vibrations of the diaphragm. This strip a, as before stated, is transparent, and from it is prepared the variable circuit-controller Z, which is represented in Fig. 3 as the positive or counterpart of Fig. 2.

The strip Z is "composed of a mixture of suitable organic material-as glue, gelatine, 8m; a dichromate salt-as of potassium, am-

monium, 8tc. a finely-pulverized electric conducting material-as carbon, metals, their conducting compounds, 850.; and water or other solvent of the organic material, by which it is brought into condition to be intimately mixed with the dichromate salt and conducting-powder and to be molded or formed into the desired shape. The quantity of each of the materials in this composition may be varied to suit the exigency of the case; but for general use good results may be obtained by the following proportions, viz: one hundred parts of gelatine dissolved in sufficient water to admit of its being formed into thin sheets, sixteen parts of potassiu m dichromate, and fifty parts of finely-pulverized carbon, intimately mixed with the dissolved gelatine before forming intoshets. A strip or sheet of this sensitized conducting material is exposed to light under the negative recordstrip a, and thus made insoluble by the combined action' of the light and the dichromate salts on the organic matter, the insolubility being in proportion to the amount of light passing through'the negative, so that the parts covered by the most opaque parts of the negative are the most removed or washed away in the subsequent washing process to which the strip or sheet is subjected. Now it will be observed that if this strip Z be interposed in an electric circuit by placing it between a metallic bed and a brush or roller adapted to cover the greatest width of the path of the sinuosities and be moved uniformly under the brush or roller, the resistance of the circuit will be varied by the changes of conductivity of the path for the current through the part of the strip is covered by the sinuous markings.

In Fig. 4 is shown how the strip Z is practically applied to reproduce by transmission over a telephone-line the original articulate sounds recorded in the receiving apparatus. In this view the strip Z passes around and is moved by the drum or cylinder at, uniformly rotated by the spring or other motor, a. The brush or roller 0 is caused to bear on the sinuous markings of the strip Z, and is connected to one end of the primary coil of the inductorium p, the other end of which is in contact with the drum m. Said primary circuit also includes the battery q. The secondary coil of the inductorium is. included in the line 7, at

the other end of which is the telephonic receiver s.

The principles of operation in this transmitting apparatus are similar in all essential features to those of ordinary telephonic apparatus,the impulses in the secondary circuit in this case being induced by variations in the resistance of the primary circuit automatically produced by the movement of the variablere sistance circuit-controller Z.

It will be understood that the variable-resistance path may be produced on the sensitized conducting sheet, plate, or film ina direct manner, by exposing the same to the action of light rays controlled or directed thereon by the vibrations of a diaphragm in the receiving and recording instrument, such asis shown in Fig. 1; and my invention contemplates such production of the variablea'esistance circuit-controller; but in most applications of the invention I prefer to first produce the record of sound-waves and therefrom produce the variable-resistance circuit controller, especially when it is desired to retransmit the recorded sound-Waves over several lines, by making the desired number of variable rcsistance circuitcontrollers from the one transparent negative record. This transparent negative may be retained as a permanent record of the message ICC received. and retransmitted and variable-resistance circuit-controllers prepared from it at any subsequent time.

The sinuous markings on the strip a may be increased in .width by means of the lens if, placed betweelrthe shield g and the strip a, which deflects the rays passing through the hole h.

Having now described my invention, what I claim, and desire to secure by Letters Patent,

1; As a means for rctransmitting recorded articulate sound-waves, a circuit controller consisting of an electrically-conductive film,

plate, or sheet having a sinuous variable-resistance path corresponding to the sound-waves.

2. The combination, with a circuit-controller consisting of an electrically conductive film, plate, or sheet having on its surface a va- LEO BOOK, JR.

\Vitnesses:

H. D. WILLIAMs, ALFRED SHEDLOOK. 

